Efficency of scope statement with a lot of empty cells

I've gotten mixed signals on whether or not to use non_empty behavior in SQL 2008 so I am wondering what I can do to make the following more efficient:

SCOPE ([Peanut Butter],[Radios],[Measures].[Denominator]);   
    this = [Measures].[Distinct Lightbulb Qty];   
END SCOPE;   

[Peanut Butter] is a set of about 5 dimension members. [Radios] is a set of about 30,000 dimension members, 29,000 of which will come back empty. [Distinct Lightbulb Qty] is a distinct count measure that counts [Lightbulb Key]s. The options I am considering are:

1. Add a hierarchy to the [Radio] dimension to indicate whether the [Radio] has [Peanut Butter].

2. Something like CREATE SET [Nonempty Radios] AS NONEMPTY([Radios], [Measures].[Row Qty]);

But I'm not sure if either of these would help or if there is something else I should try.